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Terahertz (THz) quantum cascade lasers (QCLs) are technologically important laser sources for the THz range but are complex to model. An efficient extended rate equation model is developed here by incorporating the resonant tunneling mechanism from the density matrix formalism, which permits to simulate THz QCLs with thick carrier injection barriers within the semi-classical formalism. A self-consistent solution is obtained by iteratively solving the Schrödinger–Poisson equation with this transport model. Carrier–light coupling is also included to simulate the current behavior arising from stimulated emission. As a quasi-ab initio model, intermediate parameters, such as pure dephasing time and optical linewidth, are dynamically calculated in the convergence process, and the only fitting parameters are the interface roughness correlation length and height. Good agreement has been achieved by comparing the simulation results of various designs with experiments, and other models such as density matrix Monte Carlo and non-equilibrium Green's function method that, unlike here, require important computational resources. The accuracy, compatibility, and computational efficiency of our model enable many application scenarios, such as design optimization and quantitative insights into THz QCLs. Finally, the source code of the model is also provided in the supplementary material of this article for readers to repeat the results presented here, investigate, and optimize new designs. [ABSTRACT FROM AUTHOR]

Research was conducted on heteroepitaxial interfaces in the GaInP/GaAs superlattices prepared on GaAs substrates usig high resolution x-ray diffraction and dynamical simulations. Indium purging was identified as the cause of strained layer at the GaInP/GaAs inteface while the indium-poor strained layer at the GaAs/GaInP was determined to be responsible for pressure differences detected in the gas lines.

A long wavelength infrared focal plane array based on type-II InAs/GaSb superlattices was fabricated and characterized at 80 K. The noise equivalent temperature difference in the array was measured as low as 23 mK for an integration time of 0.129 ms. The noise behavior of the detectors was properly described by a model based on thermal, shot, read out integrated circuit, and photon noises. The noise of the imager was dominated by photon noise for photon fluxes higher than 1.8×1015 ph s-1 cm-2. At lower irradiance, the imager was limited by the shot noise generated by the dark current or the noise of the testing system. The superlattice detector did not create 1/f noise for frequencies above 4 mHz. As a result, the focal plane array did not require frequent calibrations. [ABSTRACT FROM AUTHOR]

The emission behavior of binary-binary type-II InAs/GaSb superlattice photodiodes has been studied in the spectral range between 8 and 13 μm. With a radiometric calibration of the experimental setup the internal and external quantum efficiencies have been determined in the temperature range between 80 and 300 K for both the negative and positive luminescences. The negative luminescence efficiency approaches values as high as 35% without antireflection coating. An analytic description of the temperature dependence of the internal quantum efficiency around a zero-bias voltage allows for the determination of the coefficient for electron-hole-electron Auger recombination Γn=1×1024 cm6 s-1. For an n-type material, the minority-carrier lifetime is provided as a function of band gap and temperature, explaining the strong decrease of the minority-carrier lifetime in the case of an n-type residual background exceeding 1×1016 cm-3. Furthermore, an analytic expression of the quantum efficiency for the radiation upon forward-bias conditions is given. [ABSTRACT FROM AUTHOR]

Examines two GaAs/GaInP superlattices grown on GaAs substrates by low-pressure metalorganic chemical vapor deposition using high resolution x-ray diffraction measurements and simulations by solving Tagaki-Taupin equations. Tools used to study the heteroepitaxial interfaces on an atomic layer scale; Description of superlattices; Effect of substrate miscut on the measured superlattice period.

Investigates the metalorganic vapor deposition of a number of heterojunctions using reflectance anisotropy (RA). Characterization of the heterojunctions; Experimental details; RA observations of heterojunction growth.

Discusses the in situ reflectance anisotropy (RA) measurements of InAs (100) metalorganic chemical vapor deposition (MOCVD) growth under optimal growth conditions. Experimental details; Diagram of the RA system; Effects of the MOCVD reactor on the growth.

We report the most recent advance in the area of type II InAs/GaSb superlattices that have cutoff wavelength of ∼3.7 μm. With Ga[sub x]In[sub 1-x] type interface engineering techniques, the mismatch between the superlattices and the GaSb (001) substrate has been reduced to <0.1%. There is no evidence of dislocations using the best examination tools of x-ray, atomic force microscopy, and transmission electron microscopy. The full width half maximum of the photoluminescence peak at 11 K was ∼4.5 meV using an Ar[sup +] ion laser (514 nm) at fluent power of 140 mW. The integrated photoluminescence intensity was linearly dependent on the fluent laser power from 2.2 to 140 mW at 11 K. The temperature-dependent photoluminescence measurement revealed a characteristic temperature of one T[sub 1]=245 K at sample temperatures below 160 K with fluent power of 70 mW, and T[sub 1]=203 K for sample temperatures above 180 K with fluent power of 70 and 420 mW. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]